A parasitic tropical disease, also known as bilharzia, that is caused by flukes (parasitic flatworms) called schistosomes, and acquired from infested rivers, lakes or other waters. The larvae penetrate the skin and develop in the body into adult flukes, which settle in the veins of the bladder and the intestines. Their eggs cause inflammatory reactions; there can be bleeding and ulceration in the bladder and intestinal walls, and the liver can be affected.
The initial symptom of infestation is generally tingling and an itchy rash where the flukes have entered the skin. An influenza like illness can arise many week later, when the adult flukes produce eggs. Subsequent symptoms include blood in the urine or faeces, lower back or abdominal pain, and enlargement of the spleen or liver. Complications of long term infestation include bladder tumours, kidney failure and liver cirrhosis.
Treatment is with the drug praziquantel. No vaccine is available, so those people visiting infested areas should avoid bathing or wading in fresh water.